Chapter 5 Vital Signs
Vital signs reflect the body’s physiologic status and provide information critical to evaluate
homeostatic balance. Vital signs include four critical assessment areas: temperature, pulse,
respiration and blood pressure. These four signs form baseline assessment data necessary for an
ongoing evaluation of a client’s condition. If the nurse has established the normal range for a client,
deviations can be more easily recognized.
Many factors such as the temperature of the environment, physical exertion, and the effects of
illness cause vital signs to change, sometimes outside normal range. Vital signs should be taken at
regular intervals. The more critical the client’s condition, the more often these signs need to be
taken and evaluated. They are not only indicators of a client’s present condition, but also provide
clues to a positive or negative change in status. An alteration in vital signs may signal the need for
medical or nursing intervention.
Vital signs are a quick and efficient way of monitoring a client’s condition or identifying
problems and evaluating the client’s response to intervention. Vital signs and other physiological
measurements are the basis for clinical problem solving. Assessment of vital signs allows the
nurse to identify nursing diagnoses, implement planned interventions, and evaluate nursing effect.
When the nurse learns the physiological variable values influencing vital signs and recognizes the
relationship of vital sign changes to other physical assessment findings, precise determinations of
the client’s health problems can be made. Careful measurement techniques ensure accurate
findings.
Guidelines for Taking Vital Signs
The nurse assesses vital signs whenever a client enters a health care agency. Vital signs are
included in a complete physical assessment or obtained individually to assess a client’s condition.
The nurse must be able to measure vital signs correctly, understand and interpret the values,
communicate findings appropriately, and begin interventions as needed. The following guidelines
assist the nurse to incorporate vital sign measurement into nursing practice:
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1. The nurse caring for the client is responsible for vital signs measurement. The nurse should
obtain the vital signs, interpret their significance, and make decisions about interventions.
2. Equipment should be functional and appropriate for the size and the age of the client.
Equipment should be selected based on the client’s condition and characteristics. For example, an
adult-size blood pressure cuff should not be used for a child.
3. The nurse should know the client’s normal range of vital signs. A client’s usual values may
differ from the standard range for that age or physical state. The client’s usual values serve as a
baseline for comparison with findings taken later. Thus a nurse can detect a change in condition
over time.
4. The nurse should know the client’s medical history, therapies, and prescribed medications.
Some illnesses or treatments cause predictable vital sign changes. Most medications affect at least
one of the vital signs.
5. The nurse should control or minimize environmental factors that may affect vital signs.
Measuring the pulse after the client exercises may yield a value that is not a true indicator of the
client’s condition.
6. The nurse should use a systematic approach when taking vital signs. Each procedure
requires following a step-by-step approach to ensure accuracy.
7. The physician decides the frequency of vital signs assessment according to the client’s
condition. In the hospital the physician orders a minimum frequency of vital sign measurements
for each client. Following surgery or treatment interventions, vital signs are measured frequently
to detect complications.
8. The nurse may use vital sign assessment to determine indications for medication
administration. The physician may order certain cardiac drugs to be given only within a range of
pulse or blood pressure. The nurse does not administer these drugs if vital sign assessment is
outside of these limits. Taking vital signs to determine clinical changes and trends is useful in
making therapeutic decisions.
9. The nurse should analyze the results of vital sign measurement. The nurse is often in the
best position to assess all clinical findings about a client. Vital signs are not interpreted in isolation.
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The nurse must also know other physical signs or symptoms and be aware of the client’s ongoing
health status.
10. The nurse should verify and communicate significant changes in vital signs. Baseline
measurements allow a nurse to identify changes in vital signs. When vital signs appear abnormal,
it may help to have another nurse or a physician repeat the measurement. The nurse informs the
physician of abnormal vital signs and documents and reports vital sign changes to nurses working
the next shift.
SectionⅠBody Temperature
Physiology of Body Temperature
The body temperature reflects the balance between the amount of heat produced by body
processes and the amount of heat lost to the external environment. There are two kinds of body
temperature: core temperature and surface temperature. The core temperature is the temperature of
deep tissues, such as the cranium, thorax, abdominal cavity, and pelvic cavity, and remains
relatively constant. The surface temperature is the temperature of the skin, the subcutaneous and
the fat tissue. Surface temperature fluctuates depending on blood flow to the skin and the amount
of heat lost to the external environment.
Heat Production
Thermoregulation requires the normal function of heat-production processes. Heat is
produced in the body through metabolism. Cellular chemical reactions require energy in the form
of ATP. The amount of energy used for metabolism is the metabolic rate. Activities requiring
additional chemical reactions increase the metabolic rate. As metabolism increases, additional heat
is produced. When metabolism decreases, less heat is produced. Heat production occurs during
rest, voluntary movements, involuntary shivering, and nonshivering thermogenesis.
Voluntary movements such as muscular activity during exercise require additional energy.
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The metabolic rate can increase up to 2000 times normal. Heat production can increase up to 50
times normal.
Shivering is an involuntary body response to temperature differences in the body. The
skeletal muscle movement during shivering requires significant energy. Shivering can increase
heat production 4 to 5 times greater than normal. Heat is produced to equalize body temperature.
Nonshivering thermogenesis occurs primarily in neonates. Vascular brown adipose tissue
present at birth is metabolized for heat production.
Heat Loss
Heat loss and heat production occur simultaneously. The skin’s structure and exposure to the
environment result in constant, normal heat loss through radiation, conduction, convection, and
evaporation.
Radiation is the transfer of heat between two objects without direct contact by
electromagnetic waves. Blood flows from the core internal organs carrying heat to skin and
surface blood vessels. The amount of heat carried to the surface depends on the extent of
vasoconstriction and vasodilation regulated by the hypothalamus. Heat radiates from the skin to
any surrounding cooler object. Radiation increases as the temperature difference between the
objects increases.
Peripheral vasodilation increases blood flow to the skin to increases radiant heat loss.
Peripheral vasoconstriction minimizes radiant heat loss. Up to 85% of the human body’s surface
area radiants heat to the environment. However, if the surroundings are warmer than the skin, the
body absorbs heat through radiation.
The nurse increases heat loss through radiation by removing clothing or blankets. The client’s
position enhances radiation heat loss (e.g., standing exposes a great radiating surface area and
lying in a fetal position minimizes heat radiation). Covering the body with dark, closely woven
clothing also reduces the amount of radiation heat lost.
Conduction is the transfer of heat from one object to another with direct contact. When the
warm skin touches a cooler object, heat is lost. When the temperatures of the two objects are the
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same, conductive heat loss stops. Heat conducts through solids, gases, and liquids. Conduction
normally accounts for a small amount of heat loss. The nurse increases conductive heat loss when
applying an ice pack or bathing a client with cool water. Applying several layers of clothing
reduces conductive loss. The body gains heat by conduction when contact is made with materials
warmer than skin temperature, such as applying a warm pack or bathing a client with warm water.
Convection is the transfer of heat away by air movement. Heat is first transferred to air
molecules directly in contact with the skin. Air currents carry away the warmed air. As the air
current velocity increases, convective heat loss increases. An electric fan promotes heat loss
through convection. Convective heat loss increases when moistened skin comes into contact with
slightly moving air.
Evaporation is the transfer of heat energy when a liquid is changed to a gas. During
evaporation, approximately 0.6 calorie of heat is lost for each gram of water that evaporates. The
body continuously loses heat by evaporation. About 600 to 900 ml a day evaporates from the skin
and lungs, resulting in water and heat loss.
By regulating perspiration or sweating, the body promotes additional evaporative heat loss.
Millions of sweat glands located in the dermis of the skin secrete sweat through tiny ducts on the
skin’s surface. When body temperature rises, the anterior hypothalamus signals the sweat glands to
release sweat. During exercise and emotional or mental stress, sweating is one way to lose
excessive heat produced by the increased metabolic rate.
People who lack sweat gland function are unable to tolerate warm temperatures because they
cannot cool themselves adequately. Diaphoresis is visual perspiration of the forehead and upper
thorax. When diaphoresis occurs, the body temperature is reduced. A lowered body temperature
inhibits sweat gland secretion.
Evaporation is the main heat loss when environment temperature is higher than body
temperature.
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Regulation of Body Temperature
Body temperature is precisely regulated by physiological and behavioral mechanisms. For the
body temperature to stay constant, and within the normal range, the relationship between heat
production and heat loss must be maintained. This relationship is regulated by neurological and
cardiovascular mechanisms.
Neural and Vascular Control
The hypothalamus, located between the cerebral hemispheres, controls body temperature the
same way a thermostat works in the home. A comfortable temperature is the “set point” at which a
heating system operates. In the home a fall in environmental temperature activates the furnace,
whereas a rise in temperature shuts the system down. The hypothalamus senses minor changes in
body temperature. The anterior hypothalamus controls heat loss, and the posterior hypothalamus
controls heat production.
When nerve cells in the hypothalamus become heated beyond the set point, impulses are sent
out to reduce body temperature. Mechanisms of heat loss include sweating, vasodilation
(widening of blood vessels), and inhibition of heat production. If the hypothalamus senses the
body’s temperature lower than set point, signals are sent out to increase heat production by muscle
shivering or heat conservation by vasoconstriction (narrowing of blood vessels) of surface blood
vessels. Lesions or trauma to the hypothalamus or spinal cord, which carries hypothalamic
messages, can cause serious alterations in temperature control.
Behavioral Control
Humans voluntarily act to maintain comfortable body temperature when exposed to
temperature extremes. When the environmental temperature falls, a person can add clothing, move
to a warmer place, raise the thermostat setting on a furnace, increase muscular activity by running
in place, or sit with arms and legs tightly wrapped together. In contrast, when the temperature
becomes hot, a person can remove clothing, stop activity, lower the thermostat setting on an air
conditioner, seek a cooler place, or take a cool shower. The ability of a person to control body
temperature depends on (1) the degree of temperature extreme, (2) the person’s ability to sense
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feeling comfortable or uncomfortable, (3) thought processes or emotions, and (4) the person’s
mobility or ability to remove or add clothes. Body temperature control is difficult if any of these
abilities are absent or lost. Infants can sense uncomfortable warm conditions but need assistance in
changing their environment. Older adults may need help in detecting cold environments and
minimizing heat loss. Illness and decreased level of consciousness or impaired thought processes
result in an inability to recognize the need to change behavior for temperature control. When
temperature becomes extremely hot or cold, health-promoting behaviors have a limited effect on
controlling temperature.
Factors Affecting Body Temperature
The site of temperature measurement (oral, rectal, axillary, tympanic membrane, esophageal,
pulmonary artery, or even urinary bladder) is one factor that determines the client’s temperature
within a narrow range. For healthy young adults the average oral temperature is 37℃. In clinical
practice, nurses learn the temperature range of individual client. No single temperature is normal
for all people.
Table 8-1 Average Temperature and Normal Range
Site
oral
rectal
axillary
Average Temperature
37℃
37.5℃
36.5℃
Normal Range
36.3~37.2℃ (97.3~99.0℉)
36.5~37.7℃ (97.7~99.9℉)
36.0~37.0℃ (96.8~98.6℉)
Many factors affect the body temperature. Changes in body temperature occur when the
relationship between heat production and heat loss is altered by physiological or behavioral
variables. The nurse must be aware of these factors when assessing temperature variations and
evaluating deviations from normal.
Circadian rhythms
Body temperatures normally change 0.5 to 1℃ over 24 hours. Temperature drops between 2
and 6 AM and peaks between 1 and 6PM in clients who work days and sleep nignts. Temperature
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patterns are not automatically reversed in people who work at night and sleep during the day. It
takes 1 to 3 weeks for the cycle to reverse. In general, the circadian temperature rhythm does not
change with age.
Age
Temperature regulation is labile during infancy because of immature physiological
mechanisms. This can continue until puberty. Infant temperature may respond drastically to
changes in the environmental. Special care is needed to protect newborns from environmental
temperature change.
With aging the normal mean temperature is lower. Thus a temperature that seems normal in a
young adult may represent a fever in an older adult. The older adult has a narrower range of body
temperature than the younger adult. With aging, control mechanisms deteriorate and sensitivity to
temperature extremes increases.
Hormone level
Women generally have greater variations in body temperature than men.
Hormone changes during ovulation and menstruation cause body temperature fluctuations.
When progesterone level is low, the body temperature is lower than the baseline level. During
ovulation, greater amounts of progesterone enter into the circulatory system and raise the body
temperature to previous baseline level or by about 0.3℃ to 0.6℃ above basal temperature.
Body temperature changes also occur in women during menopause. Women who have stopped
menstruating may experience period of intense body heat and sweating lasting from 30 seconds to
5 minutes. There may be intermittent increase in skin temperature of up 4℃ during these periods,
referred to as hot flashes. This is due to the instability of the vasomotor controls for vasodilatation
and vasoconstriction.
Exercise
Muscle activity requires an increased blood supply and an increased carbohydrate and fat
breakdown. This increased metabolism causes an increase in heat production. Any form of
exercise can increase body temperature. Prolonged, strenuous exercise can temporarily raise body
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temperatures up to 38.3℃ to 40℃.
Medication
Some medications can influence temperature, such as anaesthetic and febrifuge.
Stress
Physical or emotional stress, such as anxiety, can raise body temperature through hormonal
and neural stimulation. Stimulation of the sympathetic nervous system can increase the production
of epinephrine and norepinephrine, thereby increasing metabolic activity and heat production.
Nurse may anticipate that a highly stressed or anxious client could have an elevated body
temperature.
Environment
Environmental temperature extremes can raise or lower body temperature. The changes
depend on the extent of exposure, air humidity, and the presence of convection currents.
Ingestion of hot/cold liquids
Drinking hot or cold liquids can cause slight variations in actual oral temperature readings.
Smoking
Smoking cigarettes or cigars can increase body temperature measurement.
Alterations in Body Temperature
Elevated Body Temperature
Changes in body temperature outside the normal range affect the set point. These changes can
be related to excess heat production, excessive heat loss, minimal heat production, minimal heat
loss, or any combination of these alterarions. The nature of the change affects the type of clinical
problems a client experiences.
Fever
A body temperature above the usual range is called fever or hyperthermia. It occurs because
heat loss mechanisms are unable to keep pace with excess heat production, resulting in an
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abnormal rise in body temperature. A single temperature reading may not indicate a fever, so some
people recommend determining a fever based on several temperature reading at different times of
the day compared to the normal for that person at that time, in addition to physical signs and
symptoms of infection.
A true fever results from an alteration in the hypothalamic set point. Pyrogens such as
bacteria cause a rise in body temperature. When they enter the body, pyrogens act as antigens,
triggering the immune system. Hormone-like substances are released to promote the body’s
defense against infection. These hormones also trigger the hypothalamus to raise the set point. To
meet the new higher set point, the body produces and conserves heat. Several hours may pass
before the body temperature reaches the new point. During this period the person experiences
chills, shivers, and feels cold, even though the body temperature is rising. The chill phase resolves
when the new set point, a higher temperature, is achieved. During the next phase, the plateau, the
chills subside and a person feels warm and dry. If the new set point has been “over shot” or the
pyrogens are removed, the third phase of a febrile episode occurs. The skin becomes warm and
flushed because of vasodilation. Diaphoresis assists in evaporative heat loss. When the fever
“breaks”, the client becomes afebrile.
Fever is an important defense machanism. Mild temperature elevations up to 39℃ enhance
the body’s immune system. A fever is usually not harmful if it stays below 39℃. During a febrile
episode, white blood cell production is stimulated. Increased temperature reduces the
concentration of iron in the blood plasma, suppressing the growth of bacteria. Fever also fights
viral infections by stimulating interferon, the body’s natural virus-fighting substance.
During a fever, cellular metabolism increases and oxygen consumption rises. The body
metabolism increases 13% for every Celsius degree of temperature elevation. Heart and
respiratory rates increase to meet the metabolic needs. The increased metabolism uses energy that
produces additional heat. A prolonged fever can weaken a client by exhausting energy stores.
Increased metabolism requires additional oxygen. If the demand for additional oxygen cannot be
met, cellular hypoxia (inadequate oxygen) occurs. Cerebral hypoxia produces confusion.
Interventions during a fever may include oxygen therapy. The regulatory mechanism used to
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compensate for fever places a client at risk for fluid volume deficit. Water loss through increased
respiration and diaphoresis can be excessive. Dehydration can be a serious problem for older
adults and children with low body weights. Maintaining optimum fluid volume status is an
important nursing action.
Heat exhaustion occurs when profuse diaphoresis results in excess water and electrolyte loss.
Caused by environmental heat exposure, the signs and symptoms of fluid volume deficit are
common during heat exhaustion. First aid includes transporting the client to a cooler environment
and restoring fluid and electrolyte balance.
An elevated body temperature related to the body’s inability to promote heat loss or reduce
heat production is hyperthermia. Any disease or trauma to the hypothalamus can impair heat loss
mechanisms. Malignant hyperthermia is a hereditary condition of uncontrolled heat production.
Malignant hyperthermia occurs when susceptible persons receive certain anesthetic drugs.
Prolonged exposure to the sun or high environmental temperatures can overwhelm the body’s
heat loss mechanisms. Heat also depresses hypothalamic function. These conditions cause heat
stroke, a dangerous heat emergency. Clients at risk include those who are very young or very old,
or have cardiovascular disease, hypothyroidism, diabetes, or alcoholism. Also at risk are those
who take medications that decrease the body’s ability to lose heat or who exercise or work
strenuously. Signs and symptoms of heat stroke include giddiness, confusion, delirium, excess
thirst, nausea, muscle cramps, visual disturbances, and even incontinence. The most important
sign of heatstroke is hot, dry skin.
Victims of heatstroke do not sweat because of severe electrolyte loss and hypothalamic
malfunction. Vital signs reveal a body temperature sometimes as high as 45℃, tachycardia, and
hypotension. As the condition progresses, a client becomes unconscious with fixed, unreactive
pupils. Permanent neurological damage occurs unless cooling measures are rapidly started.
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Classification of Fever (Oral Temperature as an example)
Table 8-2 Classification of Fever
C
Mild
Moderate
Severe
Profound
37.5℃一 37.9℃
38.0℃一 38.9℃
39.0℃一 40.9℃
>41℃
F
99.5℉一 100.2℉
100.4℉一 102.0℉
102.2℉一 105.6℉
>105.8℉
Patterns of Fever
Fevers also serve a diagnostic purpose. Fever patterns differ depending on the causative
pyrogen. The increase or decrease in the amount of pyrogens results in fever spikes and declines at
different times of the day. The duration and degree of fever depends on the pyrogen’s strength and
the ability of the individual to respond.
Constant Fever
The body temperature sustains between 39~40℃ that demonstrates little fluctuation of less
than 1℃ within 24 hours. It can be seen in pneumonia and typhoid.
Remittent Fever
The body temperature has great fluctuation above the normal more than 1℃ within 24 hours
and cannot return to normal temperature level. It can be seen in septicemia and rheumatic fever.
Intermittent Fever
The body temperature fluctuates greatly in 24 hours, which may suddenly rise above the
normal then suddenly fall to the normal or below the normal. The body temperature alternates
regularly between a period of fever and a period of normal temperature levels. It can be seen in
malaria and tuberculosis.
Irregular Fever
The body temperature irregularity alternates between a period of fever and a period of normal
temperature values. It can be seen in influenza and cancer.
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Hypothermia
A body temperature below the lower limit of normal 35℃ is called hypothermia．Heat loss
during prolonged exposure to cold overwhelms the body’s ability to produce heat，causing
hypothermia．Hypothermia is classified by core temperature measurements (Table 8-3)．It can be
accidental or unintentional，such as falling through the ice of a frozen lake．Hypothermia may be
intentionally induced during surgical procedures to reduce metabolic demand and the body’s need
for oxygen．
Table 8-3 Classification of Hypothermia
Mild
Moderate
Severe
lethiferous
C
F
32℃一 35℃
30℃一 32℃
< 30℃
23 一 25℃
89.6℉一 95.0℉
86.0℉一 89.6℉
< 80.0℉
73.4—77.0℉
Accidental hypothermia develops gradually and may go unnoticed for several hours. A client
suffers uncontrolled shivering, loss of memory, depression, and poor judgment. As the body
temperature falls below 34.4℃, heart and respiratory rates and blood pressure fall. The skin
becomes cyanotic. If hypothermia progresses, a client experiences cardiac dysrhythmias, loss of
consciousness, and becomes unresponsive to painful stimuli. The assessment of core temperature
is critical when hypothermia is suspected．A special low-reading thermometer may be required
because standard devices do not register below 35℃．
Nursing Process and Thermoregulation
Knowledge of the physiology of body temperature regulation helps a nurse to assess the
client’s response to temperature alterations and to intervene safely．Independent measures can be
implemented to increase or minimize heat loss, promote heat conservation，and increase client
comfort．These measures add to the effects of medically ordered therapies during illness．Many
measures can also be taught to family members, parents of children, or other caregivers.
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Assessment
Sites
The four most common sites for measuring body temperature are the mouth, rectum, axillary
and tympanic membrane.
To ensure accurate temperature readings, each site must be measured correctly. The
temperature obtained varies depending on the site used but should be between 36.0℃ and 37.5℃.
Rectal temperatures are usually 0.5℃ higher than oral temperatures. Axillary temperatures are
usually 0.5℃ lower than oral temperatures. Each of the common temperature measurement sites
has advantages and disadvantages. The nurse chooses the safest and most accurate site for the
client. The same site should be used when repeated measurements are necessary.
Thermometers
There are three types of thermometers: mercury-in-glass thermometers, electronic
thermometers, and disposable thermometers．Each device measures temperature in the centigrade
or Fahrenheit scale．Electronic thermometers allow the nurse to convert scales by activating a
switch．When it is necessary to convert temperature readings, the following formulas can be
used：
1. To convert Fahrenheit to Centigrade，subtract 32°from the Fahrenheit reading and multiply
the result by 5/9．
(F-32)×5/9=C
Example：(104℉一 32℉)×5/9=40℃
2. To convert Centigrade to Fahrenheit，multiply the centigrade reading by 9/5 and add 32°to
the product．
(9/5×C) +32=F
Example：(9/5×40℃)+32°=104℉
Glass Thermometer
The mercury-in-glass thermometer is the most familiar. It is a glass tube sealed at one end
with a mercury-filled bulb at the other. Exposure of the bulb to heat causes the mercury to expand
and rise in the enclosed tube．The 1ength of the thermometer is generally marked with centigrade
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calibrations．The range is about 35℃ to 42℃. The degrees on a thermometer are subdivided into
gradients of 0.1℃. The farthest point reached by the mercury in the tube is the temperature
reading．The mercury will not fluctuate or fall unless the thermometer is shaken vigorously．
Three types of glass thermometers are the oral, the axillary, and the rectal. The oral
thermometer is slender, allowing for greater exposure of the bulb against the blood vessels in the
mouth. The axillary thermometer is shorter and thicker than the oral type. It can be used to
measure temperature at any site. The rectal thermometer has a blunt end designed to prevent
trauma to the rectal tissues during insertion.
The time delay for recordings and the easy breakability are disadvantages of mercury-in-glass
thermometers. Advantages are the 1ow price, wide availability, and reliable accuracy．
Electronic Thermometer
The electronic thermometer consists of a rechargeable battery-powered display unit, a thin
wire cord，and a temperature-processing probe covered by a disposable plastic sheath. 0ne form of
electric thermometer uses a pencil-like probe. Separate nonbreakable probes are available for oral
and rectal use．The oral probe can also be used for axillary temperature measurement．Within 20 to
50 seconds of insertion, a reading appears on the display unit. A sound signals when the peak
temperature reading has been measured.
Another form of electronic thermometer is used exclusively for tympanic temperature. An
otoscope-1ike speculum with an infrared sensor tip detects heat radiated from the tympanic
membrane. Within 2 to 5 seconds of placement in the auditory canal, a reading appears on the
display unit. A sound signals when the peak temperature reading has been measured.
The advantages of electronic thermometers are that they can be inserted immediately, their
readings appear within seconds, and they are easy to read. Their expense is a major disadvantage．
Disposable Thermometer
Disposable, single-use thermometers are thin strips of plastic with chemically impregnated
paper. They are used for oral or axillary temperatures, particularly with children．They are inserted
the same way as an oral thermometer and used only once. Chemical dots on the thermometer
change color to reflect the temperature reading．0nly 45 seconds are needed to record a
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temperature．
Another form of disposable thermometer is a temperature-sensitive patch or tape．Applied to
the forehead or abdomen, the patch changes color at different temperatures．
Both forms of disposable thermometers are useful for screening temperatures, especially with
newborns.
Nursing Diagnosis
The nurse identifies assessment findings and clusters defining characteristics to form a
nursing diagnosis．For example，an increase in body temperature, flushed skin, skin warm to touch,
and tachycardia indicate the diagnosis, hyperthermia．The nursing diagnosis identifies the client’s
risk for altered body temperature or an actual temperature alteration．
Once a diagnosis is determined, the nurse must accurately select the related factor or
etiology．The related factor allows the nurse to select appropriate nursing interventions．In the
example of hyperthermia, a related factor of vigorous activity will result in much different
interventions than a related factor of febrile illness．
Table 8-4 Nursing Diagnosis and Diagnosis Foundation
Nursing diagnosis
Hyperthermia
Hypothermia
Ineffective thermoregulation
Diagnostic foundation
Increased body temperature above usual range
Flushed skin, skin warm to touch
Increased pulse and respiratory rate
Herpetic lesions of the mouth
Decreased body temperature
Pale, cool skin
Decreased pulse and respiratory rate
Feelings of cold and chill
Older adult or infants, weak
Inability to adapt to environmental temperature
Planning
Clients at high risk for alterations in body temperature require an individualized care plan
directed at maintaining normothermia and reducing risk factors．Education is important so clients
can participate in maintaining normothermia．This is particularly the case for parents who need to
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know how to take action at home when an infant or child develops a temperature alteration．The
care plan for clients with actual temperature alterations focuses on restoring normothermia,
minimizing complications, and promoting comfort．The severity of a temperature alteration will
influence the nurse’s priorities in the care of a client. The nurse care plan supports the client’s
goals.
Goal: Restore and maintain normothermia.
Outcome
Temperature maintained within normal range during environment changes
Goal: Minimize complications of altered body temperature.
Outcomes
Client’s blood pressure, pulse, and respirations are within normal limits
Client’s skin integrity maintained
Client’s nutritional intake meets body needs
Client’s mucous membranes are moist
Client is able to participate in ADL activities
Client’s skin is warm and pink
Client reports sense of rest and comfort
Goal: Reduce risk of altered body temperature.
Outcomes
Client identifies risk factors for altered body temperature
Client practices measures to prevent body temperature alteration
Implementation
Nursing Interventions for Client with Fever
Assessment
•Obtain body temperature during each phase of febrile episode．
•Assess for contributing factors such as dehydration, infection, or environmental
temperature．
•Identify physiological response to temperature.
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Obtain all vital signs．
Observe skin color．
Assess skin temperature．
Observe for shivering and diaphoresis．
Assess client comfort and well-being．
•Determine phase of fever 一 chill, plateau, fever break．
Intervention
•Promote heat loss and lower the temperature. Limit physical activity to decrease heat
production, reduce external covering on client’s body to promote heat loss through radiation and
conduction．If fever continues, physical therapies can be used to lower the temperature, such as
applying ice packs to axilla and groin areas or bathing with alcohol-water solutions．Lower the
temperature with medication if necessary. Take temperature after lowering the temperature
physically for 30 minutes, record the readings.
•Intensify the observation of client’s conditions. Take temperature once every four hours for
the client with severe fever, four times per day as body temperature reduces to 38.5℃ and twice
per day for three days after body temperature returns normal. Observe the pattern, the extent and
the course of fever. Observe client’s respiration, pulse, blood pressure, face color, shivering and
diaphoresis when taking client’s temperature. Assess for contributing factors such as dehydration，
infection，or environmental temperature．Observe therapeutic effect. Observe the intake of liquids
and the output of urine. Contact physicians promptly when find abnormal conditions.
•Provide nutrients to meet increased energy needs．Provide measures to stimulate appetite，
and offer well-balanced meals．Provide fluids at least 3000ml per day for client with normal
cardiac and renal functionl to replace fluids lost through insensible water loss and sweating．
•Promote comfort and prevent complications. Allow rest periods. Control temperature of the
environment without inducing shivering．Provide oral hygiene and keep oral moist to prevent oral
infection. Keep clothing and bed sheet dry to increase comfort and heat loss through conduction
and convection．
•Provide psychological care. Meet client’s reasonable requirements. Provide health education
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about fever.
Nursing Interventions for Client with Heatstroke
The best treatment for heatstroke is prevention．The nurse teaches clients to avoid strenuous
exercise in hot humid weather, to drink fluids such as clear fruit juices before, during，and after
exercise，to wear light，loose-fitting，light-colored clothing，to avoid exercising in areas with poor
ventilation，to wear protective covering over the head when outdoors，and to expose themselves to
hot climates gradually．
First aid treatment for victims of heatstroke include moving the client to a cooler
environment，reducing clothing covering the body, placing wet towels over the skin, and using
oscillating fans to increase convective heat loss．Emergency medical treatment may include
intravenous fluids and hypothermia blankets．
Nursing Interventions for Client with Hypothermia
The priority treatment for hypothermia is to prevent a further decrease in body temperature．
• Control environment temperature at 22~24℃.
• Elevate body temperature. Add clothes, wrap the client in blankets, and give heating
blankets or hot packs to prevent heat loss. Provide hot 1iquids such as soup for a conscious client．
• Clients are monitored closely for cardiac irregularities and electrolyte imbalances. Observe
the vital signs, take temperature once at least per hour until the temperature returns normal and
stability.
• Eliminate pathogeny.
• Health education. Prevention is the key for clients at risk for hypothermia and frostbite．
Prevention involves educating clients, family members, and friends. Clients most at risk
include the very young, the very old and persons debilitated by trauma, stroke, diabetes, drug or
alcohol intoxication, sepsis, and Raynaud’s disease. Mentally ill or handicapped clients may fall
victim to hypothermia because they are unaware of the dangers of cold conditions. Fatigue, skin
color (blacks are more susceptible), malnutrition, and hypoxemia also contribute to the risk of
frostbite. Persons without adequate home heating, shelter, diet, or clothing are also at risk.
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Evaluation
All nursing interventions are evaluated by comparing the client’s actual response to the
outcomes of the care plan．This reveals whether goals of care have been met．After any
intervention the nurse measures the client’s temperature to evaluate for change．In addition, the
nurse will use other evaluative measures such as palpation of the skin and assessment of pulse and
respirations．If therapies are effective，body temperature will return to a normal range，other vital
signs will stabilize and the client will report a sense of comfort．
Section Ⅱ Pulse
The pulse is the rhythmical throbbing of arteries produced by the regular contraction of the
heart. The number of pulsing sensations occurring in per minute is the pulse rate．
Physiology and Regulation
Forming of Pulse
Blood flows through the body in a continuous circuit．Electrical impulses from the sinoatrial
(SA) node travel through heart muscle to stimulate cardiac contraction．Approximately 60 to 70 ml
(stroke volume) of blood enters the aorta with each ventricular contraction．The arterial walls
expand to compensate for the increase in pressure. As the ventricle of the heart is in diastole,
arterial walls return to original status by its own elasticity and peripheral resistance. The expansion
and retraction of the aorta sends a wave through the walls of the arterial system that can be felt as
a light tap on palpation. The pulse is the palpable bounding of the blood flow．A light tap can be
felt by palpating an artery lightly against underlying bone or muscle．
Factors Influencing Pulse Rate
Normal pulse rate is the same as the rate of the ventricular contraction of the heart. Healthy
adult pulse rate can range between 60~100 beats per minute in quiet state. Pulse rate can be
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affected by many factorts.
Age
Normally the pulse rate varies among different age group. The pulse rates are the fastest in
infants; children’s pulse rates are faster than that of adults and adults’ pulse rates are fewer than
that of older adults.
Table 8-5 Normal Pulse Rates at Varies Ages
Age
normal range of pulse rate (beats/min)
Infants
Toddlers
Preschoolers
School agers
Adolescents to adults
Older adults
120~160
90~140
80~110
75~100
60~100
70~100
Sex
After puberty, the average male pulse rate is slightly lower than the female.
Exercise
The pulse rate normally increases with activity. Short-term exercise can increase pulse rate.
Long-term exercise conditions the heart，resulting in lower rate at rest and quicker return to resting
level.
Stress
In response to stress, sympathetic nervous stimulation increases the overall activity of the
heart. Stress increases the rate as well as the force of the heartbeat. Fear and anxiety as well as the
perception of severe pain stimulate the sympathetic system.
Position Change
When a person assumes a sitting or standing position, blood usually pools in dependent
vessels of the venous system. Pooling results in a transient decrease in the venous blood returning
to the heart and subsequent reduction in blood pressure and increase in heart rate. Pulse rate
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decreases when client is lying down.
Medications
Atropine can increase heart rate. Digitalis can decrease the heart rate.
Hemorrhage
Loss of blood increases pulse rate.
Temperature
Fever can cause an increased pulse rate. Decreased pulse rate is often seen with hypothermia.
Poor Oxygenation
Any condition resulting in poor oxygenation of blood increases pulse rate, such as chronic
pulmonary disease or anemia.
Character of the Pulse and Observation of Abnormal Pulse
Pulse Rate
When assessing the pulse, the nurse must consider the variety of factors influencing pulse
rate．A combination of these factors may cause significant changes．If the nurse detects an
abnormal rate while palpating a peripheral pulse，the next step is to assess the heart rate．The heart
rate provides a more accurate assessment of cardiac contraction．
Two common abnormalities in pulse rate are tachycardia and bradycardia．
Tachycardia is an abnormally elevated heart rate，above 100 beats per minute in quiet adults．It
is seen in the clients with fever, anemia, hemorrhage and hyperthyroidism.
Bradycardia is a slow rate, below 60 beats per minute in quiet adults．It is seen in the clients
with atrioventricular block, increased intracranial pressure, and hypothyroidism.
Pulse Rhythm
Normally a regular interval of time occurs between each pulse or heart beat．An interval
interrupted by an early or late beat or a missed beat indicates an abnormal rhythm or dysrhythmia．
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Intermittent Pulse
Intermittent Pulse is also called premature beat. It means one pulse missing during regular or
irregular pulse patterns, in which the rhythm is irregular and uneven. It can be called bigeminy or
trigeminy if one pulse absents every one or two normal pulses. This can be seen in
cardiomyopathy, myocardial infarction, digitalis intoxication, and transient symptoms caused by
excited emotion or fear. Intermittent pulse threatens the heart ability to provide adequate cardiac
output, particularly if it occurs repetitively. The nurse identifies an intermittent pulse by palpating
an interruption in successive pulse waves or auscultating an interruption between heart sounds. An
electrocardiogram (ECG) is necessary to define the pulse dysrhythmia.
Children often have a sinus dysrhythmia, which is an irregular heartbeat that speeds up with
inspiration and slows down with expiration. This is a normal finding and can be verified by having
the child hold his or her breath; the heart rate should then become regular.
Pulse Deficit
The pulse deficit is that pulse rate is less than heart rate. An inefficient contraction of the
heart that fails to transmit a pulse wave to the peripheral pulse site creates a pulse deficit．Pulse
deficits are frequently associated with dysrhythmias．It can be seen in clients with atrial fibrillation.
To assess a pulse deficit the nurse and a colleague assess radial and apical rates simultaneously
and then compare rates．
Strength
The strength or amplitude of a pulse reflects the volume of blood ejected against the arterial
wall with each heart contraction and the condition of the arterial vascular system leading to the
pulse site．Normally the pulse strength remains the same with each heartbeat．Pulse strength may
be graded or described as strong, weak, thready, or bounding．It is included during assessment of
the vascular system．
Bounding Pulse
Bounding pulse denotes an increased stroke volume, which can be palpated by fingertips
slightly. It is often seen with fever, hyperthyroidism, and aortic incompetence.
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Thready Pulse
The pulse is weak and diminished, which is barely palpated by fingertips. It often occurs with
massive hemorrhage, shock, and aortic stenosis.
Alternating pulse
The pulse alternates between increased and diminished patterns along with strong and weak
contraction of the ventricles. Common causes are hypertensive heart disease, myocardial
infarction.
Water Hammer Pulse
The abrupt distension and quick collapse of the pulse is palpated following the increased
cardiac output with resultant pulse pressure surges. It often occurs with hyperthyroidism, aortic
incompetence.
Dicrotic Pulse
A pulse marked by a double beat, with the second beat weaker than the first. It can be an
indication of dilated cardiomyopathy.It has a systole peak and a diastole peak (in contrast to pulsus
bisferiens, which has two peaks in systole.)
Paradoxical Pulse
The pulse is obviously weak or not palpable on inspiration. It results from the declined
strokes by the left ventricle on inspiration. Common causes are pericardial effusion and
constrictive pericarditis.
Equality
The nurse should assess both radial pulses to compare the characteristics of each. A pulse in
one extremity may be unequal in strength or absent in many diseases, such as thrombosis, aberrant
blood vessels, or aortic dissection. The carotid pulse should not be measured simultaneously
because excessive pressure may stop blood supply to the brain.
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Nursing process and Pulse Determination
Assessment
When assessing the pulse, the nurse should collect the following data: the client’s general
condition, such as age, sex, status of an illness and treatment; the pulse rate, rhythm, strength,
equality, factors influencing pulse and arterial wall elasticity.
A healthy, normal artery feels straight, smooth, and soft. Older people often have inelastic
that feel twisted and irregular upon palpation. Pulse assessment is helpful to determine the general
state of cardiovascular health and the response to other system imbalances．
Nursing Diagnosis
Tachycardia，bradycardia，and dysrhythmias are defining characteristics of many nursing
diagnosis and are considered along with other assessment data, such as activity intolerance,
anxiety, fear, fluid volume deficit, gas exchange impaired, hyperthermia, and hypothermia.
Nursing Plan
The nursing care plan includes interventions based on the nursing diagnosis identified and the
related factors; the expected outcomes generally are that the clients can tell the normal range and
physiological changes of the pulse; and the clients can cooperate with the treatment and care.
Implementation
·Instruct the clients to rest to decrease heart energy consuming. Oxygen administration can
be provided according to the client’s condition.
·Observe the clients’ condition closely. Instruct the clients to take medicine on time and
observe the reactions of the medicine. Tell the clients to keep first-aid medicines along with them.
·Provide mental support. Let the clients to keep steady mood.
·Health education: Stop smoking and drinking alcohol, take light and digestible diet, keep
bowels smooth. Teach the clients to monitor the pulse prior to taking medicines that affect the
heart rate. Tell the clients to report any notable changes of heart rate or rhythm to health care
provider. Teach the clients and family members the basic first-aid skills.
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Evaluation
The nurse evaluates the therapeutic effect by assessing the pulse rate, rhythm, strength, and
equality; the clients’ mental status, cooperation with treatment and nursing; and the clients’
knowledge about health．
Section Ⅲ Blood Pressure
Blood pressure is the lateral pressure on the walls of an artery by the flowing blood under
pressure from the heart．Systemic or arterial blood pressure，the blood pressure in the system of
arteries in the body, is a good indicator of cardiovascular health．Blood flows throughout the
circulatory system because of pressure changes．It moves from an area of high pressure to an area
of low pressure．
The heart’s contraction forces blood under high pressure into the aorta．The peak of
maximum pressure when ejection occurs is the systolic pressure. When the ventricles relax, the
blood remaining in the arteries exerts a minimum or diastolic pressure．Diastolic pressure is the
minimal pressure exerted against the arterial walls at all times．
The standard unit for measuring blood pressure is millimeters of mercury (mmHg). The
measurement indicates the height to which the blood pressure can raise a column of mercury.
Blood pressure is recorded with the systolic reading before the diastolic (e.g, 120/80mmHg )．The
difference between systolic and diastolic pressure is the pulse pressure．For a blood pressure of
120/80mmHg, the pulse pressure is 40mmHg．
Physiology of Arterial Blood Pressure
Blood pressure reflects the interrelationship among cardiac output，peripheral vascular
resistance，blood volume，blood viscosity, and artery elasticity．
Cardiac Output
Cardiac output is the volume of blood pumped into the arteries by the heart during 1 minute.
The blood pressure depends on the cardiac output and peripheral vascular resistance. When
volume increases in an enclosed space such as a blood vessel，the pressure in that space rises．Thus
as cardiac output increases，more blood is pumped against arterial walls，causing the blood
pressure to rise．Cardiac output can increase as a result of greater heart muscle contractility, an
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increase in heart rate, or an increase in blood volume．
Peripheral Resistance
Blood circulates through a network of arteries, arterioles, capillaries, venules, and
veins．Arteries and arterioles are surrounded by smooth muscle that contracts or relaxes to change
the size of the lumen．The size of arteries and arterioles changes to adjust blood flow to the needs
of 1ocal tissues．For example, when more blood is needed by a major organ, the peripheral arteries
constrict, decreasing their supply of blood. More blood becomes available to the major organ
because of the resistance change in the periphery. Normally, arteries and arterioles remain partially
constricted to maintain a constant flow of blood. Peripheral vascular resistance is the resistance to
blood flow determined by the tone of vascular musculature and diameter of blood vessels．The
smaller the lumen of a vessel, the greater peripheral vascular resistance to blood flow. As
resistance rises, arterial blood pressure rises. As vessels dilate and resistance falls, blood pressure
drops．
Blood Volume
The volume of blood circulating within the vascular system affects blood pressure．Most
adults have a circulating blood volume of 5000 ml．Normally the blood volume remains
constant．However, if volume increases, more pressure is exerted against arterial walls．For
example, the rapid, uncontrolled infusion of intravenous fluids elevates blood pressure. When
circulating blood volume falls, as in the case of hemorrhage or dehydration, blood pressure falls．
Blood Viscosity
The thickness or viscosity of blood affects the ease with which blood flows through small
vessels. The viscosity of blood depends on the proportion of blood cells to plasma, especially red
blood cells. When the viscosity rises and blood flow slows，arterial blood pressure increases．The
heart must contract more forcefully to move the viscous blood through the circulatory system.
Elasticity of Vessel Walls
Normally the walls of an artery are elastic and easily distensible. As pressure within the
arteries increases, the diameter of vessel walls increases to accommodate the pressure change.
Arterial distensibility prevents wide fluctuations in blood pressure. With aging or certain diseases,
the walls of arterioles lose their elasticity and are replaced by fibrous tissue. With a reduced
elasticity there is greater resistance to blood flow. As a result, the systemic pressure rises. Systolic
pressure is more significantly elevated than diastolic pressure as a result of reduced arterial
elasticity．
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Each factor significantly affects the others. For example, as arterial elasticity declines,
peripheral vascular resistance increases. The complex control of the cardiovascular system
normally prevents any single factor from permanently changing the blood pressure. For example,
if the blood volume falls, the body compensates with an increased vascular resistance．
Factors Affecting Blood Pressure
Blood pressure is not constant but is continually influenced by many factors during the day.
Understanding these factors ensures a more accurate interpretation of blood pressure readings.
The factors affecting blood pressure include:
Age
With age, blood pressure tends to rise and systolic pressure is elevated more significantly. To
the same age, blood pressure is generally higher in some over-weight and obese people than in
normal weight ones.
Table 8-6 Average Blood Pressure at Various Ages
Age
Newborn (1 month)
1 year
6 years
10~13 years
14~17 years
Middle adult
Older adult
Blood Pressure (mm Hg)
84/54
95/65
105/65
110/65
120/70
120/80
140~160/80~90
Gender
There is no clinically significant difference in blood pressure levels between boys and girls.
After puberty, males have higher readings. This difference is thought to be due to hormonal
variations. With menopause, women tend to have higher levels of blood pressure than men of the
same age．
Diurnal Variations
Variations may include a lower blood pressure in the morning, rising throughout the day,
peaking in late afternoon or evening, and 1owering at night．
Environment
Peripheral blood vessels meet cold and constrict, then blood pressure rises. Vessels meet hot
and expand, and then blood pressure declines. Hereby blood pressure is higher in winter than in
summer. Hot bath can decrease blood pressure.
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Body Shape
The tall and the obese usually have higher blood pressure.
Position Change
Blood pressure in standing position is higher than that in sitting position. Blood pressure in
sitting position is higher than that in lying position. A person may feel dizzy, tachycardia or faint
when he change his position from lying position to standing position who is lying for a long time
or take some antihypertensive medications—be called orthostatic hypotension.
Sites
Normally, systolic pressure is 10~20mmHg higher in right arm than that in left arm. The
difference of 20mmHg between both arms can be seen in varied arteritis, congenital artery
malformation, and thromboangiitis. Normally, systolic blood pressure is 20~40mmHg higher in
lower limbs than in arms, but the diastolic pressure is the same. If the blood pressure in lower
limbs is equal to or lower than that in the arm, it indicates lower limbs with arteriostenosis or
arterial obstruction.
Exercise
Physical activity increases the cardiac output and hence blood pressure increases. Thus 20 to
30 minutes of rest following exercise is indicated before the blood pressure can be reliably
assessed.
Stress
Anxiety, fear, and pain can initially increase blood pressure because of increased heart rate
and increased peripheral vascular resistance．
Medications
Some medications directly or indirectly affect blood pressure. Antihypertensive medications
including diuretics, beta-adrenergic blockers, vasodilators, ACE inhibitors，and calcium channel
blockers lower blood pressure．
Any condition affecting the cardiac output, blood viscosity, and compliance of the arteries
has a direct effect on the blood pressure.
Abnormal Blood Pressure
Hypertension
The most common alteration in blood pressure is hypertension. A blood that is persistently
above normal is called hypertension. The diagnosis of hypertension in adults is made when an
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average of two or more diastolic readings on at least two subsequent visits is 90 mmHg or higher
or when the average of two or more systolic readings on at least two subsequent visits is
consistently higher than 140 mmHg．An elevated blood pressure of unknown causes is called
primary hypertension. An elevated blood pressure of known causes is called secondary
hypertension. Categories of hypertension have been developed and determine medical intervention
Table 8-8 Definition and Classification of Blood Pressure (WHO/ISH)
Category
Systolic (mmHg)
Diastolic (mmHg)
Optimal
<120
<80
Normal
<130
High normal
130~139
85~89
Stage 1 (Mild)
140~159
90~99
Stage 2 (Moderate)
160~179
100~109
Stage 3 (Severe)
≥180
≥110
Systolic hypertension
≥140
<90
<85
Hypertension：
Hypertension is associated with the thickening and loss of elasticity in the arterial walls.
Peripheral vascular resistance increases within thick and inelastic vessels. The heart must
continually pump against greater resistance. As a result, blood flow to vital organs such as the
heart, brain, and kidney decreases．
Persons with a family history of hypertension are at significant risk．Obesity, cigarette
smoking, heavy alcohol consumption, high blood cholesterol 1evels, and continued exposure to
stress are also linked to hypertension. The incidence of hypertension is greater in older persons
and in blacks. When clients are diagnosed with hypertension, the nurse helps to educate them
about blood pressure values, 1ong-term follow-up care and therapy, the usual 1ack of symptoms
(the fact that it may not be “felt”), therapy’s ability to control but not cure hypertension, and a
consistently followed treatment plan that can ensure a relatively normal life-style．
Hypotension
Hypotension is generally considered when the blood pressure falls to 90/60 mmHg or below.
Hypotension can be also caused by bleeding, shock, severe burn, prolonged diarrhea and vomiting.
Orthostatic hypotension refers to the low blood pressure when the client sits or stands. It is
usually the result of peripheral vasodilatation in which the blood flow increases and the blood
flowing to main body organs decreases, especially the brain, often causing the person to feel
fainted.
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Nursing Process and Blood Pressure Determination
Assessment
The assessment of blood pressure along with pulse assessment is used to evaluate the general
state of cardiovascular health and its response to other system imbalances. The assessment
includes the client’s usual condition, such as age, sex, the state of illness and treatment, and
whether the clients have hemiplegia and dysfunctions or other complications.
Nursing Diagnosis
Hypotension, hypertension, and narrow or wide pulse pressures are defining characteristics of
many nursing diagnoses and are considered along with other assessment data. For example, the
defining characteristics of hypotension, dizziness, pulse deficit and dysrhythmia lead to a
diagnosis of decreased cardiac output. Related nursing diagnoses include activity intolerance,
anxiety, cardiac output decreasing, and fluid volume deficit.
Nursing Plan
The nursing care plan includes appropriate interventions based on the nursing diagnosis
identified and the related factors, the client’s understanding on the purpose of taking blood
pressure and cooperating with nursing and treatment．
Implementation
·Keep surroundings quiet and the temperature appropriate.
·Have light and digestible, low fat and low cholesterol, high vitamins and high fiber diet.
Limit salt intake according to the client’s blood pressure level.
·Form the habit of regular life. Have enough sleep, stop smoking and drinking alcohol,
maintain stool smoothly.
·Keep stable mood and decrease factors affecting emotion.
·Exercise appropriately.
·Monitor the clients’ blood pressure and condition closely. Instruct clients to take medicine
on time and observe reactions of medicine.
·Health instruction: Teach the clients and family members to take blood pressure and observe
the complications of hypertension and basic first-aid skills.
Evaluation
The nurse evaluates the clients’ outcomes by assessing the blood pressure following each
intervention; evaluates clients’ mental state and cooperation with treatment and nursing; and
evaluates clients’ knowledge about health.
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Section Ⅳ Respiration
Human survival depends on the ability of oxygen (O2) to reach body cells and for carbon
dioxide (CO2) to be removed from the cells. Respiration is the mechanism the body uses to
exchange gases between the atmosphere and the blood and the cells. Respiration involves external
respiration and internal respiration. External respiration refers to the exchange of oxygen and
carbon dioxide between the alveoli of lung and the pulmonary blood. Internal respiration refers to
the exchange of oxygen and carbon dioxide between the circulating blood and the cells of the
body tissues.
Inspiration refers to the intake of air into the lungs. Expiration refers to breathing out or the
movement of gases from the lungs to the atmosphere. Ventilation is also used to refer to the
movement of air in and out of the lungs.
There are two basic types of breathing: thoracic breathing and diaphragmatic breathing.
Thoracic breathing involves the external intercostals muscles and other accessory muscles, such as
the sternocleidomastoid muscles. It can be observed by the upward and outward movement of the
chest. Diaphragmatic breathing involves the contraction and relaxation of the diaphragm, and it is
observed by the movement of the abdomen.
Regulation of Respiration
Respiratory center
The respiratory center is composed of several clusters of neurons which stimulate and
regulate respiration in central nervous system. They are distributed over the cerebral cortex of the
brain, diencephalons, pons, medulla, and spinal cord. Pons and medulla oblongata control normal
respiratory rhythm. Higher centers above midbrain lie in cerebral ganglion and the cerebral cortex
of the brain. The cerebral cortex of the brain voluntarily controls ventilation and regulates activity
of brain stem center. So respiration is controlled by consciousness.
Reflex mechanisms
Respiratory center receives various impulses from respiratory organs and other systems, and
controls respiratory movement by reflex mechanisms.
Hering-Breuer reflex
As the lungs inflate, pulmonary stretch receptors activate the
inspiratory center to inhibit further lung expansion, while as lungs deflate, expiration is inhibited
and inspiration is stimulated. This is called Hering-Breuer reflex. When the lungs become
overdistended, the stretch receptors activate an appropriate feedback response that “switches off”
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the inspiration ramp and thus stop further inspiration and transform inspiration to expiration in
time for maintaining normal respiration rhythm.
Proprioceptor reflex
Proprioceptors are present in the chest wall and diaphragm and
provide information about thoracic inflation. Proprioceptors provide feedback and introduce
impulse to maintain normal respiration, which enables the strength of the contraction to be varied
if the airway resistance increases.
Defense reflex
Respiratory defense mechanisms are very efficient in protecting the
lungs from inhaled particles, microorganisms, and toxic gases. The defense mechanisms include
filtration of air, mucociliary clearance system, the cough reflex, sneeze reflex, reflex
bronchoconstriction, and alveolar macrophages.
Chemoreceptors control
Respiration is controlled by the level of carbon dioxide (CO2), oxygen (O2), and the
concentration of hydrogen ion ([H+]) in the arterial blood. Central chemoreceptors are located in
the medulla and respond to changes in [H+]. An increase in [H+] (acidosis) causes the medulla to
increase the respiratory rate and depth. A decrease in [H+] (alkalosis) has the opposite effect. The
most important factor in the control of ventilation is the level of CO2 in the arterial blood．Changes
in PaCO2 regulate ventilation primarily by their effect on the pH of the cerebrospinal fluid. When
the PaCO2 level is increased, more CO2 is available to combine with H2O and form carbonic acid
(H2CO3). This lowers the cerebrospinal fluid pH and stimulates an increase in respiratory rate. The
opposite process occurs with a decrease in PaCO2 level.
Peripheral chemoreceptors are located in the carotid bodies at the bifurcation of the common
carotid arteries and in the aortic bodies above and below the aortic arch. The peripheral
chemoreceptors respond to decrease in PaO2 and pH and to increase in PaCO2. These changes also
cause stimulation of the respiratory center.
In a healthy person an increase in PaCO2 or decrease in pH causes an immediate increase in
the respiratory rate. The PaCO2 does not vary more than about 3mmHg if lung function is normal.
Conditions such as chronic obstructive pulmonary disease (COPD) alter lung function and may
result in chronically elevated PaCO2 levels. The chemoreceptors in the carotid artery and aorta of
these clients are sensitive to hypoxemia, or low levels of arterial O2. If PaO2 levels fall, these
receptors signal the brain to increase the rate and depth of ventilation．Hypoxemia helps to control
ventilation in clients with chronic lung disease．Hypercarbia is constant in clients with chronic
lung disease. Once an elevated CO2 level fails to increase the rate and depth of breathing,
hypoxemia, also present in these clients, becomes the stimulus to increase ventilation. Because
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low levels of arterial O2 provide the stimulus that allows the client to breathe, administration of
high oxygen 1evels can be fatal for clients with chronic lung disease．
Normal respiration
The nurse assesses ventilation by determining the rate, depth, and rhythm of breathing.
Adults normally breathe in a smooth, uninterrupted pattern of 16 to 20 breaths per minute under a
quiet state. Generally thoracic breathing is seen in female, while diaphragmatic breathing is more
in male and children.
Factors influencing character of respirations
Respiration may change in certain range because of many factors.
Age
The respiratory rate varies with age. The younger the age, the more rapid the respiratory rate is.
Table 8-8 Normal Average of Respiriaory Rates for Ages
Age
Newborn
Infant (6 month)
Toddler (2 years)
Child
Adolescent and Adult
Older Adult
Rate
30~60
30~50
25~32
20~30
16~20
12~18
Sex
Female’s respiration is more rapid than male’s for the same age.
Exercise
Exercises increase rate and depth to meet the body’s need for additional oxygen.
Emotion
Some strong emotions, such as fear, anger, and nervousness, can stimulate respiratory center,
resulting in respiration pause or increased rate of respirations. Anxiety increases rate and depth as
a result of sympathetic stimulation.
Blood Pressure
Blood pressure can influence respiration when it fluctuates in a large range. If the blood
pressure increases, the respiration will decrease in rate and depth.
Others
Chronic smoking changes the lung’s airways, resulting in an increased rate.
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Acute pain increases rate and depth as a result of sympathetic stimulation. Client may inhibit
or splint chest wall movement when pain is in area of chest or abdomen.
Narcotic analgesics and sedatives depress rate and depth. Amphetamines and cocaine may
increase rate and depth.
Injury to the brain stem impairs the respiratory center and inhibits respiratory rate and
rhythm.
Mechanics of Breathing
In normal breathing, muscular work is involved in moving the lungs and chest wall.
Inspiration is an active process. During inspiration, the respiratory center sends impulse along the
phrenic nerve, causing the diaphragm contracts. Abdominal organs move downward and forward
to move air into the lungs. During a normal relaxed breath a person inhales 500 ml of air. This
amount is referred to as the tidal volume. During expiration the diaphragm relaxes and the
abdominal organs return to their original positions. The lung and chest wall return to a relaxed
position. Expiration is a passive process. The normal rate and depth of ventilation, eupnea, is
interrupted by sigh. The sigh, or prolonged deeper breath, is a protective physiological mechanism
for expanding small airways and alveoli not ventilated during a normal breath．
The accurate assessment of respirations depends on the nurse’s recognition of normal
thoracic and abdominal movements. During quiet breathing the chest wall gently rises and falls.
Contraction of the intercostals muscles between the ribs or contraction of the muscles in the neck
and shoulders, the accessory muscles of breathing, is not visible. During normal quiet breathing,
diaphragmatic movement causes the abdominal cavity to rise and fall slowly．
When breathing requires greater effort, the intercostal and accessory muscles work actively to
move air in and out. The shoulders may rise and fall, and the accessory muscles of ventilation in
the neck visibly contract. Diaphragmatic movement becomes less noticeable as costal breathing
increases．
Abnormal Respiration
A sudden change in the character of respirations may be important．Because respiration is tied
to the function of numerous body systems, the nurse must consider all variables when changes
occur. For example, a drop in respirations occurring in a client after head trauma may signify
injury to the brain stem．
A skillful nurse does not let a client know that respirations are being assessed. A client aware
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of the nurse’s intentions may consciously alter the rate and depth of breathing. Assessment can
best be done immediately after measuring pulse rate, with the nurse’s hand still on the client’s
wrist as it rests over the chest or abdomen. When assessing a client’s respirations, the nurse should
keep in mind the client’s normal ventilatory rate and pattern, the influence any disease or illness
has on respiratory function, the relationship between respiratory and cardiovascular function, and
the influence of therapies on respirations. The objective measurements of an assessment of
respiratory status include the rate and depth of breathing and the rhythm of ventilatory
movements．
Respiratory Rate
The respiratory rate is the number of respiration in breaths per minute. Breathing that is
normal in rate and depth is called eupnea. The nurse observes a full inspiration and expiration
when counting respiratory rate. Normal adult has 16 to 20 respirations per minute.
Tachypnea
Rate of breathing is regular but abnormally rapid (greater than 24 breaths per
minute). Common causes are fever, pain, over fatigue, and hyperthyroidism. It has been noted that
the relationship between the pulse rate and the respiratory rate is fairly consistent in healthy people;
the ratio is one respiration to about four heartbeats. When body temperature is elevated, the
respiratory rate increases in response to the increased metabolism. The rate increases as much as
three or four breaths per minute with every 1℃ that the temperature rises above normal.
Bradypnea
Rate of breathing is regular but abnormally slow (less than 12 breaths per
minute). It can be seen with anesthetics or sedatives overdose, and brain tumor.
Respiratory Depth
The depth of respirations is assessed by observing the degree of movement in the chest wall.
The nurse subjectively describes ventilatory movements as deep, normal, or shallow.
Deep Breathing (Kussmaul’s Respiration)
Respirations are abnormally deep but
regular. It commonly occurs with acidosis, diabetes ketoacidosis and uremia acidosis, because
increase in [H+] stimulates respiratory receptors to produce hyperventilation.
Shallow Breathing
It refers to the exchange of a small volume of air and the lungs inflate
and deflate to the minimal extent. It can be seen with respiratory muscle paralysis, chest or lung
diseases and shock.
Any condition causing an increase in carbon dioxide and a decrease in oxygen in blood tends
to increase the rate and depth of respiration. An increase in intracranial pressure depresses the
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respiratory center, resulting in irregular or shallow, slow breathing.
Respiratory Rhythm
Respiratory rhythm refers to the regularity of the expirations and the inspirations. Normally,
respirations are evenly spaced. Respiratory rhythm can be described as regular or irregular．Infants
tend to breathe 1ess regularly. Respiratory rhythm can be determined by observing the movement
of chest or abdomen.
Cheyne-Stokes Breathing
Respiratory cycle begins with slow, shallow breaths that
gradually increase to abnormal rate and depth. Then the pattern reverses，breathing slows and
becomes shallow, climaxing in periods of apnea for about several seconds (5 to 20 seconds) before
respiration resumes. It’s a cycle in which respiration gradually wax and wane in a regular pattern
with alternating periods of breathing and apnea. Periods of apnea may last for several seconds and
then the cycle is repeated. The mechanism is the depression of respiratory center or severe hypoxia,
causing the increase of PaCO2 to some extent, which result in hyperventilation. When the
accumulated carbon dioxide is blown off, the decreased level of it can’t stimulate chemoreceptors
and causes apnea. As its level increases again, the shallow and slow breathing then increase in rate
and depth again, alternating the cycle. It often occurs with congestive heart failure, increased
intracranial pressure, brain injury and uremia.
Biots Breathing
Biots breathing is a cycle pattern in which a series of normal breaths
followed by a short, irregular period of apnea. The mechanism is similar to Cheyne-Stokes
respiration. It often occurs before the breathing completely stops, with worse prognosis. The
common causes are head trauma and heart stroke.
Nodding Breathing
It is a breathing pattern in which the sternocleidomastoid muscles are
involved. The client’s head moves upward and downward with breathing. It often indicates
respiratory failure.
Sigh Breathing
It is a prolonged deeper breathing with sigh sound followed by a short
period of interval. Occasional sigh breathing is normal. It is commonly seen with emotional
dysfunction, such as nervousness and neurosis. Repeated and frequent sigh breathing often
indicates the approaching of death.
Dyspnea
It refers to a difficult, labored, or painful breathing because several factors lead to ventilation
increasing. Labored respiration usually involves the accessory muscles of respiration visible in the
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neck.
Inspiratory Dyspnea
When foreign bodies lodge in the upper respiratory tracts and cause
partial airway obstruction, the movement of air in and out of the lungs is interfered and the
inspiration is prolonged. Clients may have supclavicular, suprasternal and intercostal retractions.
The common causes are laryngeal edema or foreign bodies in trachea.
Expiratory Dysnea
When partial lower respiratory tracts are obstructed, the movement of
air out of the lungs is interfered and expiration is obviously prolonged. It is often seen with
obstructive pulmonary diseases.
Mixed Dysnea
It has characters of both inspiratory and expiratory dyspnea.
Respiratory Sound
Breath sounds can be heard by auscultating various locations over the chest with a
stethoscope. Normal respiration produces no noise.
Stertorous (Snoring) Respiration
It’s a deep breath pattern with snoring caused by
accumulated secretion in trachea and bronchus. It is mostly seen with coma or neurologic diseases.
Strident (Stridulant) Respiration
Harsh and high-pitched inspiratory sound can be heard
caused by the larynx or trachea, upper respiratory tracts obstruction. It also can be seen in infants
or children with laryngitis.
Assessment of Diffusion and Perfusion
The respiratory processes of diffusion and perfusion can be assessed by measuring the
oxygen saturation of the blood. After oxygen diffuses from the alveoli into the pulmonary blood,
most of the oxygen attaches to hemoglobin molecules in red blood cells. Blood flow through the
pulmonary capillaries provides red blood cells for oxygen attachment. Red blood cells carry the
oxygenated hemoglobin molecules to the peripheral capillaries, where the oxygen detaches
depending on the needs of the tissues.
The percent of hemoglobin that is bound with oxygen in the arteries is the percent saturation
of hemoglobin (or SaO2)．It is normally between 95％ and 100％．SaO2 is affected by factors that
interfere with ventilation, perfusion, or diffusion. The saturation of venous blood (SvO2) is lower
because the tissues have removed some of the oxygen from the hemoglobin molecules. A normal
value for SvO2 is 70％. SvO2 is affected by factors that interfere or increase the tissue’s need for
oxygen．
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Nursing Process and Respiratory Determination
Assessment
While assessing respiration, the nurse estimates the time interval after each respiratory cycle
and checks if respiration is regular or irregular in rhythm. The nurse also should assess for risk
factors, symptoms and signs of respiratory alterations. Vital sign measurement of respiratory rate,
pattern, depth, rhythm, and PaO2 allows the nurse to assess ventilation, diffusion, and perfusion.
Each measurement gives clues in determining client’s problems. It is necessary to assess the
client’s other information, such as age, the status of an illness and treatment, and whether the
client is suffering from cough, expectoration, hemoptysis, cyanosis, dyspnea, or chest pain.
Nursing Diagnosis
Respiratory assessment data define characteristics of many nursing diagnosis and are
considered with other assessment data. Nursing diagnosis related with respiration include activity
intolerance, ineffective breathing, gas exchange impairment, ineffective airway clearance, and so
on.
Nursing Plan
The nursing plan includes interventions based on the nursing diagnosis identified and the
related factors. The client can understand the purpose of taking respiration measurement and
cooperate with nursing care and treatment.
Implementation
·Provide a comfortable environment. Instruct the client to have appropriate rest and activity.
·Observe the changes of the client’s condition closely. Instruct client to take medicine on
time and observe reactions of the medicine.
·Maintain adequate hydration and nutrition.
·Oxygen inhalation and sputum aspiration are provided according to the client’s condition.
Monitor respiration, collect sputum specimen if necessary.
·Provide mental and social support.
·Health instruction: Stop smoking and drinking alcohol, form the habit of regular life, and
teach the clients and family members basic first-aid skills.
Evaluation
The nurse evaluates nursing outcomes by assessing the respiratory rate, depth, rhythm, PaO2
and each intervention. Evaluate the client’s mental status, degree of cooperation with treatment
and nursing, and understanding about health knowledge.
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Nursing Skills Improving the Functions of Respiration
Measures to clean out secretions of airway
Deep breathing and effective coughing
With client sitting upright, instruct client to breathe in slowly through nose to expand chest
and abdomen, and to hold sustained inspiration for 3 to 5 sec, then exhale slowly through mouth.
Inhalation through nose helps to warm, humidify, and filter inspired air. Sustained inhalation
stimulates surfactant production and prevents alveolar collapse (atelectasis). Provide tissues for
client to use while coughing.
After several deep breaths, instruct client to inhale deeply, hold breath for several seconds,
lean forward, and cough rapidly through an open mouth, using abdominal, thigh, and buttock
muscles. (Effectiveness of cough depends on amount of air inhaled and speed with which it is
exhaled.)
Instruct client with pulmonary condition to exhale through pursed lips and to cough
throughout exhalation in several short bursts (not at end of deep inhalation). This helps prevent
high expiratory pressures that collapse diseased airways and thus facilitates movement of
secretions along tracheo-bronchial tree.
Instruct client with abdominal incision to cross arms over pillows as abdominal muscles
contract during cough. Instruct client to use manual pressure on wound, or support incision with
palms of your hands. (This prevents incisional strain and encourages client to cough more
effectively.)
Assess client regularly and provide positive reinforcement. Encourage client to repeat deep
breathing exercises several times hourly. (Deep breathing helps to inflate alveoli and mobilize
secretions.)
Repeat cough only if it is productive of secretions. (Accumulated secretions promote
bacterial growth and interfere with ventilation, but coughing is a Valsalva maneuver and is not
indicated unless it is productive of secretions.)
Chest Percussion
Chest percussion involves striking the chest wall over the area being drained. The hand is
positioned so that the fingers and thumb touch and the hand are cupped. Percussion on the surface
of the chest wall sends waves of varying amplitude and frequency through the chest. The force of
these waves can change the consistency of the sputum or dislodge it from airway walls. Chest
percussion is performed by alternating hand motion against the chest wall, over a single layer of
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clothing and not over buttons, snaps, or zippers. It is contraindicated in clients with bleeding
disorders, osteoporosis, or fractured ribs. Caution should be taken to percuss the lung fields and
not the scapular regions to avoid trauma to the skin and underlying structures.
Use percussion for 30 to 60 seconds over an area several times a day, but up to 3 to 5 minutes
for the client with slimy secretions.
Postural drainage
Postural drainage uses positioning techniques to draw secretions from specific segments of
the lungs and bronchi into the trachea. Coughing or suctioning normally removes secretions from
the trachea. The procedure for postural drainage can include most lung segments. Because clients
may not require postural drainage of all segments, its use depends on assessment findings.
Have client remain in each position for 15 min for pulmonary toilet (5 min in position; 5 min
for percussion, vibration, and coughing; 5 min for bronchial drainage.)
The nurse should assess the client’s pulse, respiratory rates, pallor, diaphoresis, dyspnea, and
fatigue during postural drainage to evaluate the client’s tolerance. Postural drainage should carry
out 2 to 4 times a day for 15 to 30 minutes unless the client feels weak or faint.
Suctioning
Suctioning is a method to suck airway sections through oral cavity, nasopharyngeal cavity or
artificial airway to clear respiratory airway and to prevent complications, such as pneumonia,
atelectasis and choke. Any client (e.g. elder with weakness, critical, coma, anaesthetic clients) is
unable to remove sections with effective coughing must use suctioning.
Purposes
1. To maintain airway and prevent airway obstructions.
2. To promote respiratory function
3. To prevent pneumonia that may results from accumulated secretions.
Equipments
Portable or wall suction unit with connecting tubing with Y-connector if needed
Sterile water or normal saline
Sterile gloves
Sterile basin
Two pitchers with caps (contain sterile normal saline and sterile catheters respectively)
Sterile gauzes
Clean drape or towel
Gag, spatula, and tongue forceps if necessary
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Procedures
1. Assess for signs and symptoms indicating presence of upper airway secretions: gurgling
respirations, restlessness, vomitus in mouth, drooling.
2. Explain to client how procedure will help to clear airway and relieve some breathing
problems. Explain that coughing, sneezing, or gagging is normal.—relieve client’s anxiety.
3. Properly position client:
a. Place conscious client with functional gag reflex for oral suctioning in semi-Fowler’s
position with head turned to one side. Place such a client for nasal suctioning in semi-Fowler’s
position with neck hyperextended. Gag reflex helps prevent aspiration of gastrointestinal contents.
Positioning of head to one side or hyperextending neck promotes smooth insertion of catheter into
oropharynx or nasopharynx, respectively.
b. Place unconscious client in side-lying position facing nurse. Prevents client’s tongue
from obstructing airway, promotes drainage of pulmonary secretions, and prevents aspiration of
gastrointestinal contents.
4. Place towel on pillow or under client’s chin. Prevent soiling of bed linen or bedclothes
from secretions.
5. Turn suction device on and set vacuum regulator to appropriate negative pressure. (Adults:
300-400 mmHg; Children: 250-300 mmHg).
If indicated, increase supplemental oxygen to 100% or as ordered by physician.
Wear gloves.
6. Connect one end of connecting tubing to suction machine and place other end in
convenient location.
Check equipment is functioning properly by suctioning small amount of normal saline from
pitcher.
Coat distal 6-8cm of catheter with normal saline.
7. Suction
Oropharyngeal suctioning:
Without applying suction, gently but quickly insert catheter about 10 to 15cm into mouth to
pharynx. Move catheter around mouth until secretions are cleared. Do not allow catheter to “rest”
against oral mucosa. Encourage client to cough in order to move secretions from lower airway into
mouth and upper airway.
Rinse catheter and connecting tubing with normal saline in pitcher until clear.
Nasopharyngeal suctioning:
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Without applying suction, gently but quickly insert catheter into naris using slight downward
slant as client breathes in. Do not force through naris. Insert a catheter 2.5 to 4 cm; then briefly
wait as client takes deep breath and quickly insert catheter to desired area.
Pharyngeal suctioning: In adult, insert catheter about 16 cm; in older children, 8-12 cm; in
infants and young children, 4-8 cm. Rule of thumb is to insert catheter distance from tip of nose to
base of ear lobe.
Tracheal suctioning: In adult, insert catheter about 20-24 cm; in older children, 14-20 cm; in
infants and young children, 8-14 cm. In some instances turning client’s head to right helps nurse
suction left principal bronchus; turning head to left helps nurse suction right principal bronchus.
If resistance is felt after insertion of catheter for recommended distance, nurse has probably
hit carina. Pull catheter back 1 cm before applying suction.
Rinse catheter and connecting tubing with normal saline in pitcher until clear.
Artificial airway suctioning:
Without applying suction, gently but quickly insert catheter into artificial airway (best to time
catheter insertion with inspiration) until resistance is met, then pull back 1 cm.
Apply intermittent suction less than 15 seconds and slowly withdraw catheter while rotating
it back and forth. Encourage client to cough.
Rinse catheter and connecting tubing with normal saline in pitcher until clear.
Repeat steps above as needed to clear secretions. Allow adequate time (at least 1 full minute)
between suction passes for ventilation and reoxygenation.
Assess client’s cardiopulmonary status.
When artificial airway and tracheobronchial tree are sufficiently cleared of secretions,
perform nasal and oral pharyngeal suctioning to clear upper airway of secretions. After this
suctioning is performed, catheter is contaminated; do not reinsert into endotracheal or
tracheostomy tube.
8. Disconnect catheter from connecting tubing; discard into appropriate receptacle. Pull
gloves off. Turn off suction device.
9. Perform hand hygiene.
10. Prepare equipment for next suctioning.
11. Observe client for absence of airway secretions, restlessness, and oral secretions.
12. Record the amount, consistency, color, and odor of secretions and client’s response to
procedure; document client’s presuctioning and postsuctioning respiratory status.
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Oxygenic Therapy
Indication of Oxygen Therapy
The goal of oxygen therapy is to prevent or relieve hypoxia. Any client with impaired tissue
oxygenation can benefit from controlled oxygen administration. Oxygen is considered a drug that
requires a physician’s prescription for administration, because it has dangerous side effects. The
nurse must know the indication, dosage, route of administration, and potential complications of its
use.
Classification of Hypoxia
Hypoxia is classified into four categories based on the causes and characteristic of hypoxia.
Among four categories of hypoxia, oxygen therapy can raise PaO2, SaO2, and CaO2 and attain
good effect for clients with hypotonic hypoxia. Oxygen therapy may have effect on clients with
heart failure, shock, severe anemia, or carbon monoxide poisoning.
Classification of hypoxia
Characteristics
Causes
Hypotonic hypoxia
Decreased level of PaO2 and
CaO2 in arterial blood
Caused
by
a
diminished
concentration of inspired oxygen,
alterations of external respiration,
or venous blood shunting into the
arteries, such as high altitude
disease, COPD, or congenital heart
diseases
Circulatory hypoxia
Poor tissue perfusion with
oxygenated blood
Caused by shock, heart failure, and
so on
Hemic hypoxia
Inadequate or alterations of
quality of hemoglobin lead to
hemic hypoxia
Caused by anemia,
carbon
monoxide
poisoning,
or
methemoglobinemia
Histogenous hypoxia
The inability of tissues to
extract oxygen from blood
Caused by cyanide poisoning
Level of Hypoxia
Oxygen therapy and liters of oxygen flow per minute is administered according to assessment
of the client’s state of hypoxemia.
a. Mild Hypoxemia: PaO2>6.67kPa (50 mmHg), SaO2 >80%, no cyanosis. In general,
oxygen therapy is not indicated for clients in this level of hypoxemia. Clients who complain
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dyspnea may receive low flow oxygen therapy (1-2 L/min).
b. Moderate Hypoxemia: PaO2 4-6.67kPa (30-50mmHg), SaO2 60-80%. Clients have
dyspnea or cyanosis. Clients need oxygen therapy.
c. Severe Hypoxemia: PaO2 < 4kPa (30 mmHg), SaO2<60%. Clients have severe
dyspnea or may have severe cyanosis. It is absolute indication for oxygen therapy.
Oxygen Flow Rate
The flow rate of oxygen is used to regulate the amount of oxygen available to the client,
measured in liters per minute. The rate varies depending on the condition of the client and the
route of administration of oxygen. Because there is leaking and mixing with atmospheric air, the
flow rate does not exactly reflect the concentration actually inspired by the client. More precise
doses are usually prescribed in terms of percent of inspired oxygen. The physician prescribes the
flow rate of oxygen administration. The nurse should monitor closely the flow rate for the client
with lung conditions. Most clients with chronic lung diseases can tolerate oxygen with a nasal
cannula at 2 L/min but arterial blood gas analysis should be monitored closely. The nurse must
know what flow rate produces a given percentage of inspired oxygen concentration. For low or
moderate flow oxygen therapy with nasal cannula method, inspired oxygen concentration is
calculated with the following formula:
Inspired oxygen concentration (%)=21+4×oxygen flow rate (L/min)
Humidifying Oxygen
Oxygen administered from a cylinder or wall-outlet system is dry. Dry gases dehydrate the
respiratory mucous membranes. Humidifying devices are commonly used for oxygen. Distilled or
sterile water is commonly used to humidify oxygen. Oxygen passing through water picks up water
vapor before it reaches the client.
Complications of Oxygen therapy and Prevention
Prolonged administration of high concentration of oxygen can result in some complications.
Oxygen Toxicity Prolonged administration of high concentration of oxygen leads to lung
substantive changes, causing oxygen toxicity. Clients may complain of uncomfortable, pain, and
burning sensation under sternum in early stage of oxygen toxicity, then have increased respiratory
rate, nausea, vomiting, restlessness, and dry cough. Methods for preventing oxygen toxicity
include avoiding prolonged administration of high concentration of oxygen, measuring oxygen
concentration and saturation of arterial blood regularly, and observing effects and side effects of
oxygen therapy closely.
Absorption Atelectasis When clients inspire oxygen of high concentration, in alveoli
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most of nitrogen gas that is not absorbable, is replaced by oxygen. Once bronchia are obstructed
by secretions, oxygen in alveoli is absorbed rapidly and absorption atelectasis occurs. The main
symptoms of this complication include restlessness, increased respiration rate and heart rate,
raised blood pressure, dyspnea, and even coma. Prevention of obstruction in respiratory tract is
essential for preventing absorption atelectasis. Clients are often encouraged to make deep breath
and effective cough, and change body position more often to prevent stasis of secretions.
Dryness of Respiratory Secretions
Oxygen from cylinder system or wall-outlet
system is dry. Dry gases dehydrate the respiratory mucous membranes and secretions become
thick and viscous which is hard to remove. Humidification should be strengthened while
delivering oxygen to prevent dehydration of respiratory mucous membrane and dryness of
respiratory secretions.
Retrolental Fibroplasia High arterial oxygen tensions are a major factor in causing
retrolental fibroplasias in neonates, especially in preterm newborns, which may result in
irreversible blindness. The condition is caused by blood vessels growing into vitreous, which is
followed later by fibrosis. Oxygen therapy for neonates should control concentration of oxygen
and time of therapy.
Respiration Depression It occurs among clients with type Ⅱ respiratory failure who
have decreased PaO2 and increased PaCO2. Clients with type Ⅱ respiratory failure have
prolonged high level of PaCO2 in arterial blood, respiratory center in the medulla is not sensitive
to concentration of CO2 and regulation of respiration mainly depends on the stimulation to
peripheral chemoreceptors of decreased O2. When clients inspire oxygen of high concentration,
this stimulation is eliminated leading to depression of respiration and even respiration cease.
Therefore, oxygen therapy of low concentration and low flow rate is administered for clients with
type Ⅱ respiratory failure to maintain clients’ PaO2 at 8kPa.
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